Hot top



Jan. 21, 1941. G. H. JOHNSTON 2,229,507

HOT TOP Filed June 10, 1959 2 Sheets-Sheet l Jan. 21, 1941. GqH. JOHNSTON 2,229,507

HOT TOP Filed June 10, 1939 2 Sheets-Sheet 2 I ZZZ/en oy 620233 27057257222 -Patented Jan. 21, 1941 UNITED *sra'ras PATENT OFFICE llClaims- This invention relates to the casting of metal, such as steel, in ingot form, preparatory to working the metal by other processes, such as rolling and forging. An important object of the invention is to improve the quality of the ingot by controlling the cooling thereof in the mold so as to avoid the usual piping, blow holes and otherinternal defects which frequently exist under present conditions and processes. Another object of the invention is to provide a removable hot top for an ingot mold constructed in sections to facilitate its removal under certain con ditions. A further object is to provide a hot top fitted with electrical heating means to afford continuous control of the temperature during the cooling of the ingot. The invention consists in certain features and elements of construction as applied to an ingot mold, and in the method of employing the same, as herein shown and described and as indicated by th claims.

In the drawings: a

Flg. 1 is a side elevation of the upper portion of an ingot mold, including a "hot top" embodying this invention.

Fig. 2 is a vertical section of the same, taken as indicated at line 2-2 on Fig. 1.

Fig. 3 is a detail section showing one of-the electric heating units as mounted in a separable side wall of the mold, section being taken substantially as indicatedat line 3-3 on Fig. 2.

Fig. 4 is a transverse section taken as indicated at line H on Fig. 2.

Fig. 5 is a top plan view of the hot top" with the cover removed and with one of the side walls tilted away from its normal position to indicate the separable construction.

Fig. 6 is an enlarged detail section taken axially of the detachable connector for the electric heating means.

This application is a continuation in part of my application Serial No. 195,000, filed March 10, 1938.

In the preparation of steel and some other metals for working by rolling and forging, the molten metal is first poured into a mold which forms it into an ingot or billet of oblong shape, and of such cross-section as may best suit the lrerqeiairements in view of the finished shape destand in the mold for cooling they are usually placed with the long axis in vertical position, and the upper-end of the ingot tends to shrink away from the upper surface and side walls When such ingots or billets'are left toforming a pocket or so-called piping. This is due to the fact-that the outer surface cools and hardens while the interior of the ingot is still I in molten condition; and as the interior metal shrinks in cooling it flows downward or settles in the body of the ingot, thus leaving the space or void at the upper end. If a solid billet is desired this end portion must be cut oil before the rolling or other processing of the metal is proceeded with. Other flaws in the cast ingot may -be in the nature of blow-holes caused by the pocketing of gases which do not escape during the cooling because of the early formation of an outer shell or skin on the ingot. The present invention is directed toward controlling and retarding the cooling process, particularly at the upper end of the ingot, so as to overcome these and other defects resulting from present methods.

In the drawings the main body of the ingot mold is represented at A, while B designates the ingot therein. As shown, this ingot is formed with an upper end portion or head at B of somewhat reduced cross-section, and also tapered so that its extreme upper end is of slightly smaller cross-section than its lower portion where it joins the main body of the ingot B. Capping the mold A is a metallic frame or plate I on which rest the special side walls which form the mold from this point upwardly for shaping and controlling the head B of the ingot. The frame i may have a downwardly extending flange 2 at its inner margin engaging in a recess or rabbet formed at 3 around the inner edge of "the mold A so as to definitely center the frame I. The frame may also be fitted with lugs 4 extending downwardly for contactwith the outer faces of the mold A. Projecting from the upper surface of the frame I adjacent its outer margins, are lugs 5 to which there are secured the upwardly extending link members 6 which connect with a collar 1 arranged to embrace the supplemental side walls of the mold near their upper ends.

These special side walls may be made in any desired number of sections, but preferably the number corresponds with the number of lateral faces with which the ingot is formed. If the cross-section of the ingot is square or rectangular there will ordinarily be four of these side walls, each consisting of an outer metallic plate 8 and-a lining member 9 of refractory material, and preferably of one piece, for each wall unit. Interposed between the outer plate 8 and the lining U is an electric heating coil or element in flat formation, indicated at it), with a layer of heat-insulating material it interposed between this coil and the outer plate 8. Preferably, the electrical conductor I is supported in a grooved or recessed block l2 of refractory material, and a cement filler i2 between the block i2 and the refractory lining 9 assists in conducting the heat developed by the coil ill to the lining 9 the purpose of the electric heating element being to raise the temperature of the lining 9 to some- 7 thing approaching the temperature of the molten metal when the latter is poured into the mold.

In the case of a mold of rectangular crosssection the four side walls, each composed of a refractory lining 9 and the associated parts just mentioned, are supported upon the frame or plate I and are bound together near their upper ends by the retaining collar 3. The side walls when assembled are tapered externally, as well as internally, so that the collar 1 may be crowded or wedged to its final position and secured by bolts l8 connecting the collar to the upper ends of the .of said links to the lugs of the frame I.

links 6 and bolts l4 connecting the lower ends One of the side plates 8 is provided with hinge lugs I 5 pivotally connected at l6 with lugs I! extending from the channel frame [8 of a cover member. This frame may consist of two sections of channel iron, each bent to extend along one side of the cover and half way along each of the adjacent sides, with lugs 58 projecting outwardly and engaged by clamping bolts i8 for drawing .refractory member I 9 by filler material at 23 similar to that used in the side walls, though such filler is not so necessary in the case of the cover member, since it is not subjected to any considerable pressure. On the side of the frame l8 opposite the hinge lugs I! a loop or ring l8 may be attached to permit opening and closing the cover by means of a hook or rod or other suitable tackle operated from a distance to insure safety to the workman and to avoid dropping the cover suddenly onto the molten metal so as to cause it to splash when the mold is being closed just after pouring. Thus the upper reduced end or head B of the ingot is fully enclosed by the electrically heated hot top formed 0 the side walls and cover just described.

. In the other types of "hot tops" for ingot molds in which refractory material isused, the contact of the molten metal as it is poured into the mold with this material frequently causes it to break, or crack and crumble, by reason of the sudden change in temperature. By providing the electric heating elements at I and 2| it is possible vices is almost wholly avoided.

Furthermore, the heat generated by the continued flow oi'electric current through the-heat'- ing elements I0 and 2! after the metal has been poured, will serve to maintain the metal in the head portion B of the ingot in a molten state as long as it may be desirable, so that this molten metal may exert its pressure downward to facilitate the expulsion of gases and air from the body of metal in the ingot, permitting said air and gases to escape from the top of the ingot, and to be consumed or absorbed by the refractory lining material.

The side walls are assembled and held together as snugly as possible" by the collar I near their upper ends, and by contact with the lugs 5 upstanding from the plate i on which the walls rest, but in the manufacture of the refractory lining units 5 it is impossible to make them of exactly uniform size so as to correspond accurately with the area of the outer plates 8 and the electric heating units [0; however, the cement filler at i2 serves to provide a perfect cushion between each of the refractory elements and its associated wall plate 8 so that the pressure of the metal from within has no tendency to' crack the refractory member as it might otherwise do. This same filler material, if employed between the adjoining edges of the refractory bricks or blocks 9 will fill any crevices between them and thus prevent the escape, of the molten metal from the hot top. The upper and lower edges of the refractory blocks are-formed as accurately as possible for fitting snugly against the cover and against the. plate I respectively, and at the latter point a reasonably tight joint is maintained by the tension exerted through the links 6 when the bolts H! which connect them to the collar 1 are tightened.

The electric heating element in of each side wall section, may be arranged in any convenient form, as, for example, in zigzag fashion, as shown in Fig. 3, disposed in the grooved block I2 of refractory material. The terminal lugs 25 and 26' are provided with conductor pins 21 which extend through the block i 2 and the layer II and the outer metallic plate 8 for engagement with a suitable lead wire coupling. It will be understood that the pins 21 are electrically insulated from the metallic walls 8. The heating element l0 may be secured in place by rivets or screws-28 anchored in the block l2.

Fig. 5 shows one possible circuit arrangement for the heating element ll) of the four sides of the hot top"; lead wires 30 and 40 from any suitable source of current supply, not shown, are branched and provided with terminal fittings II and ll respectively, which slip onto the proecting pins 21 adjacent two opposite corners of the mold. At the other two corners short cables 50 with terminal fittings 5| are arranged to connect the heating elements of adjacent wall sections in series. sections could be thus coupled in series, or, if preferred, the four sections could be connected in parallel, each with its own separate current supply conductors. By virtue of the detachable connections between the pins 21 and terminal sockets, suchas 3|, 4| and 5|, shown in Fig. 5, the supply wires may be readily disconnected and removed when the ingotihas cooled and the top section of the mold is to be lifted off. But, preferably, the current conductors will be attached and placed in service before the ingot is poured, so that the top may be brought to a proper temperatureto avoid chilling the metal. Figs. 1

and 2 show terminals 29 for the heating element Obviously, if desired, all four cit H of the cover section with detachable circuit terminals 6| coupled thereto.

The frame or plate I which serves as a bottom for the side walls of the hot top is beveled outwardly and downwardly at its inner margins to form a definite and rather sharp reduction of cross-section between the main body B of the ingot and the head B. This also facilitates removal of the hot top and insures that the frame or bottom plate I will come away from the ingot readily. The collar 1 which binds the side walls in place, is preferably formed with a sloping upper surface at '1, designed to shed readily any molten metal which may spill onto it in the process of pouring, and thus avoid the possibility of bolts l3 becoming fastened to the collar by such metal lodging and cooling thereon. In addition to securing the upper ends of, the links 6 the bolts l3 may serve to fasten to the collar 1 the outwardly projecting hooks or lugs 1' by which the assembled parts of the hot top or casserole may be picked up and lifted clear of the head B when it has cooled.

With a construction of this character provided with heating elements by which the refractory linings 9 and I9 may be kept at any desired temperature, it becomes possible to maintain the head B of the ingot in a molten condition as long as necessary, so that the metal of the head B may continue to exert a downward force upon the molten metal in the ingot proper at B, tending to expel the air and gases therefrom and gradually working downward to fill any voids in the ingot which may result. Of course, the supply of molten metal at B insures that there will be no pipe formed in the upper end of the ingot proper, and by keeping the head 13 heated until the rest of the ingot is, practically all solidified, it results that the head portion B when allowed to cool, will solidify practically without any pipe or other fault.

It sometimes happens that the refractory lining 9 becomescracked and a portion of the mol-' ten metal interlocks with it so that the hot top cannot be removed as a unit. In such cases the separable construction of the side walls composing the hot top is of special convenience, since, upon removal of the collar 1 and the cover memher, one or .more of the side walls can be tilted outwardly away from the ingot, as indicated in dotted lines in Fig. 1. F'ig. also shows one of the walls thus tilted away from its normal position so as to move it clear of the ingot and clear of any irregularities in the contacting surfaces of the ingot and the lining, which might otherwise cause them to interlock. Incidentally, it should be noted that, although Fig. 5 illustrates an arrangement of electric cables for supplying current to the heating elements of the side wall sections, these cables would actually be removed .by disengagement from the conductor pins 21 as a preliminary step to removal of the retaining collar I. The showing of the circuit connections is therefore of a diagrammatic nature in Fig. 5; but it will be evident that if, as a matter of design, the conductor pins 21 are located near the lower ends of the side walls and below the position of the collar 1 then the collar can be removed and applied without interference from the presence of the conducting cables.

To clarify the construction indicated in Figs. 4 and 5, Fig. 6 shows one of the detachable electric connections in section, and indicates that the conductor pin 21 is riveted at its inner end to the lug 26 of the heating element, and is pro vided with a flange 2'! which serves to retain a cup-shaped insulating member 21* in a position surrounding the pin 21. The cable 30 is shown terminating as by a soldered connection in the end of a metallic sleeve 32 which is interlocked with a tubular insulating sheath 3| dimensioned to fit within the cup 21* when the sleeve 32 is telescoped over the conductor pin 21.

While there is shown and described herein certainv specific structure embodying the invention, it will be manifest to those skilled in the art that various modifications and re-arrangements of the parts may be madewithout departing from the spirit and scope of the invention, and that the same is not limited to the particular form herein shown and described, except in so far as indicated by the appended claims.

I claim:

1. In combination with an ingot mold, a removable section to enclose the head of the ingot comprising separable side wall sections each consisting of a lining member of refractory material, an outer metallic wall plate and an interposed electric heating element, a bottom plate designed to fit the top of the ingot mold and to support said side wall sections on edge, and a retaining collar embracing said side walls near their upper ends for holding them together to form an upwardly tapering chamber.

2. In the combination defined in claim 1, links connecting said bottom plate with said retaining collar to permit lifting the removable section bodily from the ingot mold by engaging the frame thus formed of the bottom plate, the collar and the links.

3. In combination with an ingot mold, a removable section to enclose the head of the ingot comprising separable side wall sections, and a bottom plate upon which they are erected to form an upwardly tapering chamber, and retaining means for holding the side walls in position including lugs upstanding from the bottom plate to engage the outer faces of the walls, said bottom plate having portions depending therefrom to engage the sides of the ingot mold for positioning the plate thereon, said plate having'a central aperture registering with the opening in the top. of the ingot mold.

4. In the combination defined in claim 3, the means for retaining the side walls in position comprising a collar embracing said side walls at a distance vertically from said bottom plate, and upwardly extending links connecting said collar to the upstanding lugs of the bottom plate.

5. In combination with an ingot mold, a removable section to enclose the head of the ingot comprising separable side wall sections sloping upwardly to form' an upwardly tapering chamher, a bottom plate on which said side walls rest formed with a central aperture to register with the openin of the ingot mold, and a retaining collar embracing said side walls, together with tension means for drawing said collar downwardly toward the bottom plate to wedge it tightly against the sloping walls.

6. A removable hot top for an ingot mold COlII-r prising separable wall sections each including a refractory member, an outer wall plate and an interposed electric heating element, a bottom plate or frame on which\ said side walls are assembled to form a chamber opening downwardly for registration withthe interior of the ingot mold, a cover including a refractory member, an .outer wall plate, and electric heating means with a marginal frame surrounding said elements,

' lugs on the cover frame and lugs on one or more able from each other by movement outwardly from the axis of the mold, and means releasably holding them in assembled relation,

8. A hot top composed of sections comprising individual separable metallic side wall plates each provided with. its individual liner of refractory material, and releasable securing means holding the sections assembled-to form a chamber, each section being independently separable from the others by movement outwardly from the axis of the chamber when the securing means is released.

9. In combination with aningot mold, means for controlling the temperature of the head of the ingot comprising a hot top having side walls which include lining means 01: refractory material, an outer metallic wall, an interposed layer of refractory material formed with a recess containing an electric heating element for raising the temperature of the refractory lining, and a cement cushion in contact with the surface of the refractory lining and filling up the recess in the layer which contains the heating element,

thus serving to transmit pressure from the lining through the recessed member to the metallic wall.

10. In combination with an ingot mold, a removable hot top to enclose the head of the ingot comprising separable side wall sections, a bottom plate on which said side walls rest formed with a central aperture to register with the opening of the ingot mold, binding means releasably holding the side wall sections in assembled relation, said sections being separable irom each other by movement outwardly fromthe axis of the chamber when the binding means is released, and means extending upwardly from the bottom plate adjacent each of said sections and positionedto limit the outward movement thereof to support thesection at such limit.

11. In combination with an ingot mold, a removable hot top to enclose the head of the ingot comprising separable side wall sections sloping upwardly to form an upwardly tapering chamber, a bottom plate on which said side walls'rest formed with a central aperture to register with the opening of the ingot mold, a removable retaining collar embracing said side walls to hold them in assembled relation, and links adjustable to exert tension between the bottom plate and said collar for wedging the latter tightly against the sloping walls, said wall sections being separable from each other by movement outwardly from the axis of the chamber when released by removal of the collar, and said links being movable outwardly to a limited extent to serve as stops and supports for limiting the outward movement of the wall sections.

GEORGE H. JOHNSTON. 

